Asphalt is a hydrocarbon-based substance primarily used in paving roads, parking lots, walkways, or the like, but also in roofing and waterproofing applications. Typically, asphalt is made at an asphalt plant and delivered hot to the construction site in a transport vehicle, such as a dump truck or the like. As is well known in the art, hot asphalt tends to stick or adhere on contact to any surface it touches, including the portion of the dump truck holding the asphalt, which is typically the bed. Consequently, workers must spend considerable time and effort manually trying to remove the asphalt from the truck beds. However, the effort is somewhat futile, since some of the asphalt invariably cannot be easily removed from the truck bed using manual implements, such as picks, scrapers or shovels. Moreover, the asphalt may even become stuck to the implements used to remove it from the truck bed. Not only is asphalt wasted as a result of this adherence, but deposits may build up in the truck beds that can be extraordinarily difficult to remove without the use of chemical agents. This may not only create delays and added expense, but also the overall quality of the paving work may decline as a result. In addition to the decline in the overall quality of work, asphalt sticking problems cause other concerns. For example, when the asphalt sticks to the truck beds or rail cars, the customer often does not get what was paid for. Furthermore, when a load of asphalt cannot be completely unloaded, the next load will not be a “full load” unless someone else cleans the transporting vehicle bed. A similar problem is also encountered with aggregate materials.
This problem with asphalt has been widely recognized for years in the industry. To some extent, a similar problem is also encountered with aggregate materials (gravel, crushed rock or stone, coal, sand, etc.), which tend to stick together and to the sides of the truck bed, especially when wet. The most common approach to cope with it is to apply release agents to the truck beds and equipment. Although this is an effective method for treating the problem, many release agents are exceedingly expensive (especially when frequent application is required) or hazardous to the environment.
For example, an early solution was to pre-treat the truck bed with hydrocarbon-based fuels, such as diesel fuel and kerosene. Although these fuels are effective in preventing the asphalt from adhering and are relatively inexpensive, they often combined with and diluted the asphalt, making it more susceptible to wear and damage when used as pavement. Additionally, these fuels are frequently linked to environmental problems, such as ground water contamination. The fumes, emissions and odors also raise health concerns because workers could be exposed through skin contact and inhalation. Such fuels are also non-renewable resources.
The health and environmental concerns associated with the use of hydrocarbon fuels as release agents led the industry to look for safer alternatives. An exemplary solution is provided in U.S. Pat. No. 4,078,104 to Martin, the disclosure of which is incorporated herein by reference. This patent discloses a release agent containing polyialkylsiloxanes (polymers), which allegedly possess effective release properties. However, this agent is not inexpensive and requires additional, specialized equipment for its application process. Other polymer-based mixtures are also ineffective because they are either unstable and react either too slowly or quickly with the asphalt (see, e.g., U.S. Pat. No. 6,143,812 to Martin et al., the disclosure of which is also incorporated herein my reference).
Since the hydrocarbon-based fuels often reacted with the asphalt, the Environmental Protection Agency (EPA) promulgated standards that require release agents to not strip or degrade the asphalt. The recent trend is toward more natural and safer products. However, most of these safer alternatives are not very effective. For example, U.S. Pat. No. 5,494,502 to DeLong, the disclosure of which is incorporated herein by reference, describes a release agent comprising of emulsions from a fatty oil of plants or animals. Since it is oil-based, this release agent may be expensive when used in large quantities. To reduce the expense, this patent proposes the use of a special foaming apparatus, which complicates the application process.
Accordingly, a need exists for a release agent that is inexpensive, readily available, environmentally friendly, and easy to apply without the need for specialized equipment. The release agent would provide a slick, long-lasting barrier on the application surface, such as a truck bed, that does not allow asphalt or aggregate materials to stick. In addition, the release agents may also have moderate anti-freezing and deicing characteristics.